1. Field of the Invention
This invention generally relates to a system and a method for facsimile transmission and more particularly to a system and a method for performing good quality facsimile transmission of document information at a high speed.
2. Description of the Prior Art
Conventionally, as means for telecommunication of document information, have been widely used telex, teletex, facsimile and personal computer to personal computer communication.
First, in case of using the telex, character information is inputted from a keyboard by typing thereof or from a paper tape reader by reading thereof preliminarily punched in the tape and then is transmitted in the form of a coded electrical signal. The telex, however, has the advantage that it cannot transmit image and graphic information except only character information. Further, the range of the character which can be transmitted by the telex is limited only to alphabets and some symbols. Data transfer rate of the telex is approximately 50 bits/second (bps). Moreover, it costs almost 3500 yen to transmit information represented by 2000 characters corresponding to an (ISO) A4 size.
Next, the teletex is the combination of a word processor and a teletype and is used to send a document which is preliminarily created by the word processor at the data transfer rate of 2400 bps. Thus, the transfer rate of the teletex is higher than that of the telex by a factor of about 50 times, and on the other hand the communication cost of the former is about a tenth that of the latter, that is, considerably lower than that of the latter. Incidentally, in Japan, has been developed a practical Japanese language teletex which can deal with kana data in addition to alphabetical data.
Furthermore, the facsimile is the process by which a document (or graphic material) is optically scanned, and the information described in the document (hereunder sometimes referred to simply as document information) is then converted by using photoelectric conversion into time series electrical signals, and the electrical signals are transmitted by communication lines and finally the information is reproduced on a sheet of paper. By this facsimile, any document information can be transmitted because an image or picture described on a document can be transmitted without any modification thereof as can be understood from the foregoing description. In addition, to transmit the document information, an operator or user has only to set the document on a facsimile system and then dial an information destination and thus the facsimile system is very easy of operation.
Further, the personal computer to personal computer communication (hereunder sometimes referred to simply as personal computer communication) is the process of transmitting coded character information by using a personal computer or a word processor as a communication terminal. The data transfer rate of the personal computer communication is nearly equal to that of the teletex, and the communication cost of the personal computer communication is low. Additionally, by the personal computer communication, image or graphic data can be transmitted through the transfer time of such data is relatively long.
Incidentally, as to a facsimile system of Group 4 (hereunder sometimes referred to simply as a G4 facsimile system) of which the practical implementation is commenced, is prescribed a "mixed mode" in which the transmission of character codes and that of an image are combined with each other as functions of a "Class 3". Further, the structure of a document and a protocol for transmission of a document in this "mixed mode" are prescribed in Recommendation T.73 ("A Document Interchanging Protocol for Telematics Services") of International Consultative Committee in International Telegraphy and Telephony (CCITT).
As described above, in case of the communication by using the telex, the data transfer rate is low and in addition the communication cost is high. Further, in this case, the characters to be transmitted are limited only to alphabetic letters. In other words, image data and graphic data cannot be transmitted by the telex.
Further, the communication of character information has encountered problems that degradation (or blurring) of character information occurs, that an amount (or redundancy) of electrical information to be transmitted is large and that the transmission time is relatively long.
In case of the mixed mode of the G4 facsimile system, characters, pictures and graphic forms can be transmitted. It is, however, necessary to convert the form of the document information composed by an existing computer or word processor (hereunder sometimes referred to as a document composition system) into the standard form of the mixed mode in accordance with the CCITT Recommendation T.73.
Moreover, by the personal computer communication system, kanji data and image data can be transmitted. However, in case where only character data are transmitted, the data transfer rate is relatively large, though a somewhat complex procedure should be taken for operating the system. In addition, in case of employing a method of transmitting a file of software for a word processor, even data on detail layout of the file bits of modifying characters and an image are transmitted. However, there is no standard data format to be employed in software used in the system. Therefore, is necessary the standardization of software used in the transmitting portion and the receiving portion of the system.
Thus, as is seen from the foregoing description, there has been no communication system which can transmit kanji, picture and graphic data, and can realize a high-quality transmission of data at a high speed by performing a simple operation, and can save communication cost.
It is accordingly an object of the present invention to provide facsimile of CCITT Group 3, Group 4 and so forth which can realize high-speed, high-quality, low-cost and simple and easy document information communication by having a function of transmitting a printer output file to another one.